Deepwater Extended Reach Well Planning through Depleted Reservoirs

Abstract

The field is operated by Shell Malaysia and is the company's first deepwater asset in Malaysia. The first phase development was delivered by 2014. The planned Phase 2 campaign aims to maintain the oil production plateau. One of the campaign objectives is to produce from the deepest untapped reservoir. However, due to the depleted nature of all 3 reservoirs located above the untapped reservoir, there is a need to drill through these depleted intervals with extremely narrow drilling margin window (less than 0.5 ppg). An added complexity is the location of the reservoir which is situated directly below the hydrates bulge of the field. Due to hyrdrates disassociation concerns by producing through the hyrdate layer, the current surface location of the well is situated 3km away from the reservoir adding ERD drilling challenges to an already complex well. Lastly, geomechanical analysis indicate that the relatively high mud weight required to maintain borehole stability in the shale intervals results in a negative margin scenario between the Stabor mudweight and the fracture gradient. To address the challenges of this well, an integrated approach between various disciplines such as Wells, Subsurface, Well, Reservois and Facilities Management (WRFM), and Subsea is a critical success factor. Every discipline plays an integral role to increase the probability of success. Some of the project enablers ongoing efforts include: Geomechanic assessment on representative fracture gradient with lower depletion constant to widen the drilling window, leveraging the learning from UK and Gulf of Mexico (GOM) experience and borehole stability subject matter expert (SME) network. Wells assessment on technologies in Managed Pressure Drilling and stress caging with optimisation in well trajectory and casing design. Collaboration between Subsea, Subsurface and Wells on geohazard assessment to move subsea top-hole location to avoid potential geohazards that adds complexity to the well. The project is going through the detailed design phase until the end of 2018. The results of the Detailed design phase will be shared during the conference.